mod_athena is an Apache-based application load balancer for large systems. It allows the HTTP server to act as a load balancer either internally to Apache's own mod_proxy (for reverse proxying), or externally to machines querying it. Arbitrary statistics are sent to the engine via a simple GET plus query-string interface, from which it will then make decisions based on chosen algorithms.
mod_auth_useragent2 is an Apache module that can be used to limit access to documents by means of the User-Agent. As an authentication method, this is really unsafe because it is easy to change the User-Agent in most browsers, but it could be used to prevent stupid bots and spiders from accessing your Web sites.
The mod_cidr_lookup is an Apache module for version 2.2 and 2.0. The mod_cidr_lookup detects client type by looking up the client's source IP address in CIDR blocks. This module sets the environment variable X_CLIENT_TYPE and the HTTP request header X-Client-Type, so it can be used in both Apache (httpd.conf) and Web applications.
mod_ftpd is an FTP server module for Apache using the authentication system in Apache to provide anonymous or user-based FTP. Alternate chroot directories for users can be provided via a plugin system to check different data sources for the information. Currently a DBM and libdbi plugin are included. Limiting the number of users that can log into the system is also provided via a plugin system, so new limiting algorithms can be easily added in. Currently only a base limiter is provided which sets an overall cap to the each virtual server.